Microwave energy amplifier



Fh;. 3, 1953 w. M. GOTTSCHALK 2,627,586

MICROWAVE ENERGY AMPLIFIER Filed Oct. 18, 1949 OUTPUT /A/l//V 70R mlvsra/l m GOTTSCf/ALK Patented Feb. 3, 1953 UNITED STATES PATENT OFFICE 2,627,586 s MICROWAVE ENERGY AMPLIFIER,

Winston M.- Gottschalk, Watcrtown, Mass aissignor to Raythcon Manufacturing Company,

Newton, Mass, a corporation of Delaware Application October '18, 1949, Serial No. 122,098

scams. (or. 315-4) This invention relates to amplifying devices, and, more particularly, to amplifying devices for electrical energy inrthe microwave region of the electromagnetic spectrum. g

It is among the objects of the present invention to provide a device of the general character specified which is relatively simple in construction and which is relatively easy and economical to fabricate and assemble. I g r Ibis afurther object of the present invention to provide an amplifying devicefor microwave energy which is reasonably frequency-insensitive up to a frequency of about 10,000 megacycles per second.

It is astill further object of the present invention to provide a device which, while capable of giving only relatively low microwave energy am.- plicatiornfor example, amplification by a factor of about 5, nevertheless is efiicient.

These, and other objects of the present invention, which will become more apparent as the detailed description progresses, are attained, in general, in the following manner.

The device contemplates the provision of an evacuated envelope containing means. for projecting an electron beam along a predetermined path. Disposed adjacent this path is a means, receptive of the microwave energy to be amplified, for defiecti ng the electron beam from said predetermined path in synchronism with the alternations of said energy, said beam being thereby caused to move along additionalpaths which are angularly displaced with respect to said predetermined path. Another means is disposed adjacent said additional paths, in longitudinally spaced relationship with respect to said deflecting means, for absorbing energy from the electron beam as it passes thereby. The amount of energy necessary to deflect the electron beam at the first above-mentioned means is relatively small, but L tioned means, substantial energy is extracted therefrom which represents an amplification of the deflecting input energy.

In the accompanying specification there shall be described, and in the annexed drawing shown,

an illustrative embodiment of the amplifying de- L vice of the present invention. It is, hows-tier, to be clearly understood that the present invention is not to be limited to the exact details herein shown and described forpurposes of illustration only, inasmuchas changes therein may be made without the exercise of invention and within the true spirit and scope of the claims hereto appended.

In saiddrawing I v, s a Fig. 1 is a moreor less. schematic representa. tion of an amplifier made in accordance with the present invention; and s V Fig. 2 is a similar view. of, the same, in perspective to more clearly show the physical and elec; trical relationships between the components thereof.

Referring now more in detail to. the. aforesaid illustrative embodiment. of the p esent .inven tion, with particular reference to the drawing illustrating the same, the miner-arm designates an evacuated envelope at one end of which there is mounted an electrongu'n l l. of-substantially conventional construction, and at the other. rid of which there is mounted a collecting electrode [2. The gun includes acathode l3, preferably, of the inclirectly-heatedtype, for supplying, upon suitable heating by a voltagesoiirce L4,, a copious flow of electrons, and appropriate electron f ocusing and accelerating electrodes. I5. The cathode l3 and collecting electrode l 2. are. ,adapted,,to have a voltage applied therebetween, for, example, by means of a voltage source lfi, ivvhereby an electron beam is projected between saidelectrodes along a-first path 'A which lies, for example, along the longitudinal axis of the en velopelll. J

Spaced from the electron .gun. l l, ai long,,th e path A, is a means, hereshown as a l efll'lel'ri system ll straddling the path A, which, v en excited by themicrowave energy .to be amplified, for example, from a two-wire line I1 whichrnay be sealed through the envelope] 0 andconn ,cted to said lecher-wire system, deflects theeleetron beam, for example, aboveandb ow,the,path.,A in synchronism with the alternations ogt sa-idenergy, so as to cause saidelectronbeam to be, projected alternately along pathsfi andC, ,While a lecher-wire system has been specifically shown, it is to be understood that other appropriate wave guiding means may be employed instead;

Preferably, the lecher-wire system is shorted at one end, as at [8, and the region in which the electron beam passes between the wires of said lecher-wire system is a quarter wave length from said shorted. end, whereby said electron beam is in the region of maximum voltage along the standing wave set up on the lecher-wire system.

Spaced from the collecting electrode l2, along the paths B and C, is a pair of two-wire lines I and 26, said lines being connected by another two-wire line 2| to straddle the three paths A, B and 0. Here, again, other appropriate wave guiding devices may be employed in place of the two-wire linesshown and described. The distances along the lines It and from the points where said lines are adjacent the paths B and C to the points of connection of said lines to the line 2! are, preferably, a half wave length, and the length of the line 2| is also, preferably, a

half wave length, the total distance from the point where the path 3 passes the line H), through the line 2!, to the point where the path C passes the line 20, preferably, always being an odd number of half wave lengths. The line 2% is shorted, as at 22, at a point a quarter wave length from the path C, and the free end of the line It may be connected to a suitable load for example, by means of a two-wire line [9' which may be connected to the ends of said line I9 and sealed through the envelope It.

In operation, the positive potential applied to the collecting electrode l2 causes the electron beam from the gun H to move along the path A centrally between the wires of the lecher-wire system I! and centrally between the two-wire i;

lines I9 and 29. When the microwave energy to be amplified is applied to the lecher-wire system H, the electron beam is deflected from the path A in synchronism with the alternations of the input so as to be alternately projected along the paths B and C. As the beam passes the line [9, it induces a voltage between the wires of said line, thus setting up a current therein. By the time the resulting wave reaches a point along the line 20 adjacent the path C, the electron beam, due to a reversal of the polarity of the input to the lecher-wire system IT, is moving along said path C to induce a voltage between the wires of the line 20 which is in phase with the first abovementioned voltage. odd number of half wave lengths between the paths B and 0 along the lines I9, 211 and 2|.

Inasmuch as the electron beam between the gun II and electrode l2 represents a heavy current, the energy absorbed by the lines [9 and 28 represents an amplification of the input to the lecher-wire system IT.

This completes the description of the aforesaid illustrative embodiment of the present invention. It will be noted from all of the foregoing that the amplifier of the present invention is simple in construction, easy and economical to fabricate and assemble, and provides emcient amplification, by a factor of about 5, of microwave energy of up to about 10,000 megacycles per second.

Other object and advantages of the present invention will readily occur to those skilled in the art to which the same relates.

What is claimed is:

l. A microwave energy amplifier comprising: an evacuated envelope containing means for prolecting a beam of electrons along a first path; means, mounted in said envelope adjacent said first path and receptive of the microwave energy This is due, of course, to the to be amplified, for deflecting said beam of electrons from said first path, whereby the same is projected alternately along additional paths which are angularly displaced from and lie on opposite sides of said first path; and a pair of resonant two-wire lines, mounted in said envelope, respectively, adjacent said additional paths, in longitudinally spaced relationship with respect to said last-named means, for inductively absorbing energy from said beam of electrons; each of said two-wire lines including a pair of conductors lying side by side along the length of said envelope.

2. A microwave energy amplifier comprising: an evacuated envelope containing means for proje-cting a beam of electrons along a first path; a lecher-Wire system, mounted in said envelope straddling said first path and receptive of the microwave energy to be amplified, for electrostatically deflecting said beam of electrons from said first path, whereby the same is projected alternately along additional paths which are angularly displaced from and lie on opposite sides of said. first path; and a pair of two-wire lines, mounted in said envelope, respectively, adjacent said additional paths, in longitudinally spaced relationship with respect to said lecher-wire system, for inductively absorbing energy from said beam of electrons.

3. A microwave energy amplifier comprising: an evacuated envelope containing means for projecting a beam of electrons along a first path; means, mounted in said envelope adjacent said first path and receptive of the microwave energy to be amplified, for deflecting said beam of electrons from said first path, whereby the same is projected alternately along additional paths which are angularly displaced from and lie on opposite sides of said first path; and a pair of two-wire lines, mounted in said envelope, respectively, adjacent said additional paths, in longitudinally spaced relationship with respect to said last-named means, for inductively absorbing energy from said beam of electrons; said twowire lines being connected by a third line which is of an electrical length equal approximately to an odd number of half wave lengths of said microwave energy, whereby said two-wire lines absorb energy of similar phase.

4. A microwave energy amplifier comprising:

an evacuated envelope containing means for projecting a beam of electrons along a first path; a lecher-wire system, mounted in said envelope straddling said first path and receptive of the micro-wave energy to be amplified, for electrostatically deflecting said beam of electrons from said first path, whereby the same is projected alternately along additional paths which are angularly displaced from and lie on opposite sides of said first path; and a pair of two-wire lines, mounted in said envelope, respectively,-adjacent said additional paths, in longitudinally spaced relationship with respect to said lecher-wire systern, for inductively absorbing energy from said beam of electrons; said two-wire lines being connected by a third line which is of an electrical length equal approximately to an odd number of half wave lengths of said microwave energy, whereby said two-wire lines absorb energy of similar phase.

5. A microwave energy amplifier comprising: an evacuated envelope containing means for pro- J'ecting a beam of electrons along a first path; means, mounted in said envelope adjacent said first path and receptive of the microwave energy 5 6 to be amplified, for deflecting said beam of elec- REFERENCES CITED trons from Sam first path whereby the Same The following references are of record in the is projected along a second path which is anfile of this patent:

gularly displaced from said first path; and a resonant structure, mounted in said envelope, ad- 5 UNITED STATES PATENTS jacent said second path, in longitudinally spaced Number Name Date relationship with respect to said last-named 2,042,321 Lindenblad May 26, 1936 means, for inductively absorbing energy from 2,180,958 Hollmann Nov. 21, 1939 said beam of electrons; said resonant structure 2,368,031 Llewellyn Jan. 23, 1945 including a pair of conductors lying side by side 10 2,444,073 Tomlin July 29, 1948 along the length of said envelope. 2,449,975 Bishop et a1. Sept. 28, 1948 2,459,724 Selgin Jan. 18, 1949 WINSTON M. GO'I'TSCHALK. 2,489,132 Herold Nov.v 22, 1949 

